Haven't tested this much lately here, but since nobody else is responding:
We no longer offer an X86 (Intel) version of our app (and never offered some parts of it in X86) so the quality of the experience would depend on how well your Chromebook emulates ARM. We do have lots of people using even our current ARM-only app happily on X86 devices, but just in general for the sake of future-proofing I'd strongly recommend getting an ARM instead of an X86 Chromebook; really the only platforms on which I'd consider a device with an X86 chip at this point are legacy PC platforms like Windows and macOS, for everything else the future belongs to ARM.
That being said, if you insist on getting an X86 Chromebook the switch to ARM-only has actually seemed to improve the TTS situation a bit; now that the entire app is in ARM we no longer have the awkward situation we used to where it would get confused and refuse to load our ARM TTS libraries because other parts of the app were in X86.